Drying apparatus having variable pressure suction zones



Feb. 25, 964

R. WIEDE MANN DRYING APPARATUS HA 2 Sheet sheet 1 Filed April 26, 1960 INVENTOR R'CHARD W EDER M NN Feb. 2 1964 R. WIEDERMANN 3,122,428

DRYING APPARATUS HAVING VARIABLE PRESSURE SUCTION ZONES Filed April 26, 1960 2 Sheets-Sheet 2 FIGA FIG.5

INVENTOR RICHARD WIEDERMANN United States Patent 3,122,428 DRYING APPARATUS HAVING VAREABLE PRESSURE SUCTION ZONES Richard Wiedermann, Egeisbach, Germany, assignor to Fleissner G.in.b.H., Egelshach, Germany Filed Apr. 26, 1%9, Ser. No. 24,840 Claims priority, application Germany May 8, 1959 7 Claims. (Cl. 34-115) The present invention relates generally to a treatment and more specifically to a drying apparatus and is directed to a suction-type drying apparatus having provision to vary the degree of suction effect at different portions thereof.

The present invention is concerned especially with drying devices of the sieve drum type, wherein a reduced or lowered fluid pressure, as compared with the atmospheric pressure, is provided in the interior of the drum. The drying device is provided with at least one suction zone, which is created in the interior of the drum by suitable means, for example, a suction nozzle, so that a desired reduced pressure can be achieved pursuant to one object of the present invention, as compared to the pressure in the remainder of the drum, which can be varied in accordance with the intended use of the apparatus.

Provision can be made for one or more of these reduced pressure zones constituted, for example, by nozzles, preferably in the area of the drum jacket and within the interior of the drum.

It is another obiect of the present invention to provide means affording the arrangement of suction zones, which exert an increased suction at the material receiving point or location so that the material adheres to the surface of the sieve drum jacket in the direction of the delivery point of the material.

it is another object of the present invention to provide means aiming at a reduction of the suction once the material has adhered to the drum jacket.

It is a further object of the present invention to provide means effectuating the suction zone to remain in a predetermined position Within the drum during the operating cycle thereof, or to cause said zone to be moved into a position Where the required suction pressure is needed.

It is a further object of the present invention to provide means obviating shrinkage in the material due to suction. In this connection, provision is made to vary the degree of suction along the effective surface of the drum, so that if, for example, a high degree of suction is desired at several points along the surface, a corresponding number of suction zones or nozzles may be provided.

The above and other objects of the invention will become further apparent from the following detailed description, reference being made to the accompanying drawings, showing preferred embodiments of the invention.

In the drawings which illustrate the best modes presently contemplated for carrying out the invention:

FIG. 1 is a side elevational view of a sieve drum drier apparatus, pursuant to the present invention, comprising two drums;

FIG. 2 is a sectional view taken on line 2-2 of FIG. 1;

PG. 3 is a vertical cross section through a sieve drum pursuant to another embodiment of the invention;

FIG. 3a is a horizontal cross section through the drum of FIG. 3;

FIGS. 4 and 5 are similar to FIG. 3a and illustrate additional embodiments; and

FIG. '6 is similar to FIG. 3 and illustrates a further embodiment.

Pursuant to the present invention, different suction zones can be provided by utilizing suction nozzles, as in FIGS. 1 and 2, or they can be formed by other provision Within the sieve drums, as in FIGS. 3 through 6. Briefly described, unless an additional fan, other than that used to create the suction, is associated with a suction nozzle, the desired effect is always obtained by making the ratio of cross section of the pipe leading to the nozzle, designated F to the cross section of the nozzle itself, designated F greater than the ratio of the cross section of the main exhaust duct from the drum, designated F to the effective drum surface, designated F Consequently, there results the following ratios:

F :F greater than F :F or F :F greater than F :F

As previously indicated, the suction nozzle is adjustable, as desired, over the extent of the sieve drum surface and in relation to the distance from the drum jacket. The nozzle is usually coaxial relative to the drum axis, however, it can also be arranged in any desired angle to the coaxial position. The preferred nozzle position is that in which the front of the nozzle conforms to the curvature of the surface of the conveyor means which carried the material to the drum. The direction of the nozzle can also be at right angles to the drum axis; the nozzle can also be curved to conform to the radius of the drum jacket.

The suction pipe for the nozzle can be shifted and it can be extended. In general, the suction pipe will ex tend up to the sieve drum fan or to the area of the lowest pressure, or greatest negative pressure.

The cross sectional area of the nozzle suction pipe and of the nozzle itself is adjustable with reference to their form and size. For this purpose, there can be provided, for example, adjustable cover plates, or louvre-type closures, which are insertable into the drum.

It is also within the scope of the present invention to effect a complete closure of one or the other cross sectionaI faces of the drum. The various suction nozzles, or suction zones, can all have a similar, or different, pressure.

As a result of the higher resistance which is encountered when the suction is increased by increasing the nozzle surface area F resulting from the increased air velocity, the air flow. velocity at P or within the nozzle pipe, is lower than that at P the exhaust duct. Since the exhausted air at F has a higher velocity than that at the nozzle surface F there results an additional air in jector effect. Depending on the ratio of F :F and F zF a multiple of the reduced or negative pressure at F, can be produced at P This is of paramount importance for the transfer of the material to be dried from the conveyor to the drying drums.

The cross-sectional nozzle surface area F can be greater than the cross sectional pipe area F Nevertheless, a greater reduced or negative pressure can be produced at P than at F the effective drum surface, if the ration F zF is greater than F :F

As previously indicated, at least one suction zone can be created also by other devices, or by combinations thereof, which consequently have substantially the same effect as that achieved with the suction nozzle. Pursuant to the present invention, a nozzle plate can so subdivide the drums and the cross section of the suction pipe, for example, into two equal zones or areas, that the intake air, which is adjacent to the drum fans is directly drawn in thereby, while the remaining air is fed to the fan over the nozzle aperture.

If two exhaust fans are used, this provides a favorable characteristic for a sieve drum, that is, the undesired axial air flows caused by the unilateral exhaust of the air, are to a great extent eliminated. It is not essential for the nozzle defining plate to subdivide the interior of the drum, and the exhaust surface of the fan, into two equal parts. It is also Within the scope of the present invention to subdivide the space into thirds, or some other fractions.

Pursuant to another embodiment of the present invention, increased suction at the point at which the material to be dried passes on to the drum is achieved by providing a fixed perforated plate for the balance of the suction drum sector.

This increased the air resistance so that normal suction is produced. The fixed perforated plate, which is provided for increasing the air resistance, should have a free air flow cross section which is smaller than the air flow cross section at the drum surface plus the constriction caused by the material to be dried.

Referring now to FIGS. 1 and 2 in detail, there is shown a sieve drum drier apparatus 20, pursuant to the present invention. As here shown, apparatus 20 comprises two perforated drums 22 and 24 mounted for rotation within a housing 26 by any suitable drive means, generally indicated at 28.

The housing is provided with an inlet opening 39 and with a discharge outlet 32. The material M, which is to be dried, is carried through the inlet 36, by an endless belt conveyor 34, to the first drum 22. Suction nozzle means such as a suction nozzle 36, as here shown, is a slotted housing member having a cross sectional suction surface F is positioned within drum 22 adjacent the delivery end of conveyor 34.

The nozzle 36 is connected to a suction pipe 33 having a cross sectional surface area F The pipe extends from the nozzle to the exhaust fan (not illustrated) for drum 22. Pipe 38 can have any desired cross section and, if desired, may have a funnel-shaped portion. The effective suction surface of the drum 22 is indicated at P and F indicates the remaining suction surface in the region of the fan, or cross sectional area of the main exhaust duct 4%.

Journals for the drums are indicated at 42. It will be understood that the similar parts in drum 24 bear the same reference numerals as in drum 22. It will be understood that the greatest suction is efiected at the outlet of the conveyor 34, at the point where the material M rides onto the perforated surface of the drum 22, the suction being reduced outwardly thereof sufficient to retain the material on the lower surface of drum 22.

The material moves in the direction of the arrows 44- and 46. The suction increases again in drum 24 at the point where the material leaves drum 22, rides onto drum 124 and reduces as it travels over the upper half of the atter.

A stationary baffle 48 along the upper half of drum 22 reduces the suction therealong and facilitates the disengagement of the material from drum 22 as it reaches a point opposite the nozzle 36 in drum 24. Similarly, a fixed bafiie 59 along the lower half of drum 24 reduces the suction therealong and facilitates the discharge of the dried material through outlet 32.

Referring now to FIGS. 3 and 3a in detail, there is shown a sieve drum drier mechanism 52 which is rotated in the direction of arrow 54. The perforated drum jacket is indicated by reference numeral 1. The interior of the drum is divided into two equal parts by suction nozzle means such as a nozzle plate 3 which defines a nozzle opening 4 between plate 3 and wall 56 of the drum. A fixed plate or bafile 2 extends along half the surface of jacket 1, with closure plates extending from the ends of plate 2 to the jacket.

Due to the utilization of the nozzle plate 3, the air drawn into the drum, in the vicinity of the fan (not illustrated) is divided into two streams 58 and 5%. Air intake stream 58 is drawn directly into the fan arid out the duct 4t). Air intake stream 6% is drawn through the nozzle opening 4 before it is drawn into the fan and exhausted from duct 40.

This provides a highly desirable characteristic in a sieve drum having a single exhaust fan, in that undesirable axial air flow, usually produced in a unilateral exhaust of the air, is obviated to a great extent. it will be understood that it is not essential that nozzle plate 3 should subdivide the interior of the drum and the exhaust surface 62 of the fan into two equal parts, since plate 3 can be angularly displaced from the illustrated position thereof.

FIG. 4 illustrates a modification of the drum device shown in FIG. 3. In drum device 64, provision is made for suction nozzle means such as two nozzle plates 6 and 7, within the drum interior, to define three nozzle apertures a, b and c to provide an excellent radial air flow. More specifically, there is a first air flow stream 65 through nozzle (1, a second air flow stream dis through nozzle 1; and a third air flow stream 70 through nozzle c. It is within the scope of the present invention to vary or change the shapes of plates 6 and 7 to alter the air flows. For example, plate 7 could be provided with a radially directed strip, or both plates 6 and 7 could be mounted in adjustable relation to the drum jacket 1.

Referring now to FIG. 5, in detail, there is shown another modification. Drum device 72 is provided with suction nozzle means such as angular nozzle plates 74 and 7-5 within the drum jacket 1. The construction of FIG. 5 provides for increased suction at the edges of the drum so as to provide a better drying action for the material on the drum. The plates 74 and '76 subdivide the exhaust cross section on the fan side into equal zones 0, b and 0" but the plates 74 and 76 are also effective to divide the nozzle surfaces or sections, so that nozzle surfaces [1 and c are smaller than nozzle surface b to provide the required suction force. The resultant air flow streams are indicated at 78, 8t) and 82.

Referring now to FIG. 6 in detail, there is shown a device 84 in which relatively high suction is provided in the area where the material M is received from the conveyor 11. An imperforate cover plate 2 within the drum makes the upper region thereof ineffective by preventing air flow through the adjacent portion of jacket 1. A erforated cover plate 8 is provided at the lower portion of the drum jacket in order to increase the air resistance. This plate is adjustable.

In addition, provision is made at the lower jacket portion for a shorter imperforate plate 9. The arrow 35 indicates the direction of rotation and the arrows 8S indicate the air flow into the drum. Due to the arrangemer of the various plates within the drum, the greatest suction effect is produced in the area of the drum indicated by reference numeral it adjacent the delivery end of conveyor 11. The perforated plate 8 for increasing the air resistance should have a free flow cross section which is smaller than the flow cross section of the drum jacket, including the constriction caused by the material M thereon.

It is within the scope of the present invention to have excessive pressure in some of the air flow zones within the drums.

Various changes and modifications may be made without departing from the spirit and scope of the present invention, and it is intended that such changes and modifications be embraced by the annexed claims.

Having thus described the invention, what is claimed as new and desired to be secured by Letters Patent is:

1. Drying means, means providing a plurality of suction zones within said drum means, one zone being defined at the portion of said drum which supports material to be dried, said zone defining means including suction nozzle means for said zone, and means to provide suction pressure at said one zone different from the remaining suction pressure Within said drum, said nozzle means comprising a slotted housing member, and a conduit extending therefrom.

apparatus comprising perforated drum 2. A fluid treatment device according to claim 1, wherein said nozzle means includes a conduit extending into said drum from an opening in a side thereof and including walls defining a flared outer nozzle portion connected to said conduit which is effective over a predetermined area of the interior periphery of said drum.

3. Drying apparatus comprising perforated drum means, means providing a plurality of suction zones within said drum, means for directing material to be dried to said drum at one zone thereon, said suction zones providing suction effective on said drum surface to support material thereon, said one zone being defined at the portion of said drum which supports material to be dried in the vicinity of the location at which material is directed to said drum, and means to provide suction pressure in said drum effective at said one zone greater than the remaining suction pressure within said drum to provide a strong suction attraction of the material to said drum at said one zone, said zone defining means including suction nozzle means for said one zone, said nozzle means comprising a slotted housing member and a conduit extending therefrom.

4. A fiuid treatment device for fibers and similar materials, comprising a rotatable perforated drum, means for applying suction to the interior of said drum effective through the perforations to hold materials to said drum as it is rotated, comprising a single rotary fan arranged to withdraw fluid from the interior of said drum, means for delivering material to said drum at a location at the periphery thereof for transportation around said drum away from said delivery location as said drum is rotated, the material being held solely by the suction acting through the perforations on said drum, means for rotating said drum, and stationary nozzle plate means at the interior of said drum including spaced walls converging toward the interior of said drum and defining a passage for suction air flow through the perforations and extending inwardly from immediately adjacent the interior of said drum, said passage and the remaining portion of the interior of said drum communicating with said means for applying suction to the interior of said drum to effect increase of the suction pressure through said perforations at the portion of the periphery of said drum in alignment with said passage; said converging spaced walls of said nozzle plate means being located near the material delivery location of said drum.

5. A fluid treatment device for fibers and similar materials, comprising a rotatable perforated drum, means for applying suction to the interior of said drum effective through the perforations to hold materials to said drum as it is rotated comprising a single rotary fan arranged to withdraw fluid from the interior of said drum, means for delivering material to said drum at a location at the periphery thereof for transportation around said drum away from said delivery location as said drum is rotated,

6 the material being held solely by the suction acting through the perforation on said drum, means for rotating said drum, and stationary nozzle plate means at the interior of said drum including spaced walls converging toward the interior of said drum and defining a passage for suction air flow through the perforations and extending inwardly from immediately adjacent the interior of said drum, said passage and the remaining portion of the interior of said drum communicating with said means for applying suction to the interior of said drum to effect increase of the suction pressure through said perforations at the portion of the periphery of said drum in alignment with said passage; said spaced walls including a first wall closing off the perforations of a major portion of said drum and a second wall spaced therefrom and closing off the perforations of a portion of the interior of said drum less than the remaining portions, said second wall being perforated over at least a portion thereof.

6. Drying apparatus comprising: a rotatable hollow drum having perforations in the peripheral surface thereof; a stationary suction nozzle and conduit communicating therewith situated within said drum, said suction nozzle being situated adjacent the drums surface; a main exhaust duct communicating with the interior of said drum and with said conduit and nozzle; and, an exhaust fan for applying suction in said exhaust duct; said nozzle, conduit, exhaust duct and perforated drum surface being so dimensioned that the ratio of the cross-sectional area of the conduit to the cross-sectional area of the suction nozzle is greater than the ratio of the cross-sectional area of the main exhaust duct to the perforated area of the drums surface.

7. Drying apparatus comprising: a rotatable hollow drum having perforations in the peripheral surface thereof; a stationary suction nozzle and conduit communicating therewith situated Within said drum, said suction nozzle being situated adjacent the drums surface; a main exhaust duct communicating with the interior of said drum and with said conduit and nozzle; and, an exhaust fan for applying suction in said exhaust duct; said nozzle, conduit, exhaust duct and perforated drum surface being so dimensioned that the ratio of cross-sectional area of the conduit to the cross-sectional area of the main exhaust duct is greater than the ratio of the cross-sectional area of the suction nozzle to the perforated area of the drums surface.

References Cited in the file of this patent UNITED STATES PATENTS 

1. DRYING APPARATUS COMPRISING PERFORATED DRUM MEANS, MEANS PROVIDING A PLURALITY OF SUCTION ZONES WITHIN SAID DRUM MEANS, ONE ZONE BEING DEFINED AT THE PORTION OF SAID DRUM WHICH SUPPORTS MATERIAL TO BE DRIED, SAID ZONE DEFINING MEANS INCLUDING SUCTION NOZZLE MEANS FOR SAID ZONE, AND MEANS TO PROVIDE SUCTION PRESSURE AT SAID ONE ZONE DIFFERENT FROM THE REMAINING SUCTION PRESSURE WITHIN SAID DRUM, SAID NOZZLE MEANS COMPRISING A SLOTTED HOUSING MEMBER, AND A CONDUIT EXTENDING THEREFROM. 